Twelfth hand-authored Zai-Magic preset: a true scrolling spectrogram as a
pure script -- bgx feedback slide moves the whole framebuffer left (the
time axis), persist 1 keeps the history locked, and a 64-bin vertical
write head at the right edge inks pink -> red -> orange -> yellow -> white
over a deep dark navy field that only leaves by scrolling off the left
edge. The per-frame ink is computed from the live stroke geometry (coats
= 1.12 + 1.604*wpx/segl; ink = 1.1/(coats*ratio)) so overlapping columns
accumulate to full palette strength at any fps, aspect or brush width,
with per-coat adds kept above 8-bit quantization. Half-second erase phase
drains the previous preset's framebuffer, 3s 15x fill sweep paints the
navy field, stage resizes replay the sweep. EMBEDDED_SEED_VERSION
7.14 -> 7.18.1; seed re-synced (107 presets).